The Chiltern Railway Company Limited, trading as Chiltern Railways, was a British train operating company that operated the Chiltern franchise from July 1996 until September 2026. It was a subsidiary of Arriva UK Trains from April 2009 until the end of its franchise.

Chiltern Railways was founded as M40 Trains by a group of ex-British Rail managers backed by John Laing and 3i; in June 1996, it was announced that M40 Trains had been awarded the Chiltern Railways franchise. On 21 July 1996, it took over operations from British Rail. The company promptly commenced the redoubling of the Chiltern Main Line under the Evergreen initiative and ordered the Clubman diesel multiple units (DMUs) to supplement its ex-British Rail fleet. Following the awarding of a 20-year franchise to Chiltern Railways in August 2000, Evergreen phase 2 works begun to raise line speeds around , built two new platforms at its terminus. In January 2010, a £250 million upgrade package was agreed for Evergreen phase 3, remodelling the line and permitting operations, thus greatly reducing journey times.

In August 2002, the John Laing Group became the sole owner of Chiltern Railways after buying out all other shareholders. In January 2008, shortly after John Laing's purchase by Henderson Equity Partners, the company was sold to the German publicly owned railway company Deutsche Bahn. Chiltern Railways became a subsidiary of Arriva UK Trains as a result of restructuring during early 2011. Around this time, Chiltern was considered one of the best railway operators in Britain, with Public performance measure (PPM) regularly over 90%. However, the introduction of new timetables during the 2010s was repeatedly received negatively by the travelling public. Severe disruption to Chiltern's services occurred following the collapse of Gerrards Cross Tunnel on 30 June 2005; an unplanned six week closure of the main line was forced, resulting in compensation being paid by Tesco (which planned to build a supermarket over the tunnel) to both Chiltern Railways and Network Rail.

Chiltern Railways operated commuter/regional rail passenger services from its central London terminus at Marylebone along the M40 corridor to destinations in Buckinghamshire, Oxfordshire, Northamptonshire (King's Sutton) and Warwickshire, as well as long-distance services to the West Midlands along two routes. Services on the Chiltern Main Line run from London to , and , with some peak-hour services extended to . Chiltern Railways also runs trains on the London–Aylesbury line to (some of which continue on to ), and on the Princes Risborough to Aylesbury and Oxford to Bicester branch lines. From December 2010, Chiltern began operating the Chiltern Mainline service of two peak-hour locomotive-hauled services consisting of a hauling a rake of modernised Mark 3 coaches and a Driving Van Trailer.

Chiltern Railways returned to state ownership on 20 September 2026 as part of the establishment of Great British Railways.

History Chiltern Railways originated with a number of former British Rail managers who sought to conduct a management buyout on one of the soon-to-be-created rail franchises that would be produced as a part of the privatisation of British Rail. In April 1995, they were granted a licence by the railway regulator. However, the team recognised that they lacked the resources to successfully pursue a bid, thus they secured the backing of the infrastructure investment group John Laing and the venture capital specialist 3i.

In October 1995, M40 Trains was established; the various railway managers held a combined 51% shareholding in the business, while the John Laing Group and 3i held 26% and 23% stakes respectively. The company reportedly spent £38 million in its bid for the Chiltern Railways franchise. In June 1996, the Director of Passenger Rail Franchising awarded the franchise to M40 Trains for an initial period of seven years. It was the only franchise operator to have as many as 51% of its shares controlled by its directors.

On 21 July 1996, the company commenced operations, taking over from the publicly owned British Rail. Chiltern Railways was the first railway franchise to order new rolling stock in the post-privatisation era in the form of the Class 168 Clubman DMUs. However, their introduction was marred by unreliability, in part due to their rushed entry into service in response to booming passenger demand. By April 1999, the company claimed to employ 50% more staff than it had at the start of the franchise, and to be running 25% more services than had been operated by British Rail. Meanwhile, under the terms of the franchise agreement, the annual subsidy provided by the British government was gradually reduced.

During early 1999, the ownership of M40 Trains underwent substantial changes; the John Laing Group opted to increase its shareholding in the venture to 84% via the purchase of shares from their previous holders; the outstanding 16% of shares were owned by several members of the former British Rail management team.

In March 2000, the Shadow Strategic Rail Authority announced that both M40 Trains and the British transport group Go-Ahead had been shortlisted to bid for the next Chiltern franchise. In August 2000, M40 Trains was awarded the new franchise, which was set to run for 20 years, conditional on various investments being made across that period. On 3 March 2002, the new franchise period began.

In August 2002, John Laing acquired the remaining 16% of shares in M40 Trains that it did not already own. In September 2006, John Laing was purchased by the global investment firm Henderson Equity Partners in exchange for £887 million.

During December 2004, Chiltern Railways took over operation of passenger services on the to branch line from First Great Western Link. In June 2006, M40 Trains was invited by the Department for Transport (DfT) to lodge a bid to operate the Snow Hill Lines, then operated by Central Trains, as part of the letting of the West Midlands franchise. However, this bid was not successful.

During mid-2005, Chiltern Railways' services were heavily disrupted by the collapse of Gerrards Cross Tunnel. In 1996, the British retailer Tesco sought to build a supermarket near railway station; despite the local council's initial objection to the scheme, it was approved by the Deputy Prime Minister John Prescott in July 1998. Due to a lack of available space, Tesco started building a tunnel over the active railway line to provide suitable land for the development. On 30 June 2005, the partially-constructed tunnel collapsed; nobody was injured, but a complete closure of the line was enacted for over six weeks before being permitted to reopen on 20 August 2005. Tesco paid an estimated £200million of compensation to both Chiltern Railways and Network Rail for the disruption; the retailer also pledged to fund a media campaign to win back passengers lost by the route's unplanned closure. The tunnel's construction resumed in January 2009. In late November 2010, the completed store was opened.

In July 2007, Henderson Equity Partners announced its intention to sell on Laing Rail along with the Chiltern Railways franchise. Amongst the parties to express interest in acquiring the company were the transport groups Arriva and Go-Ahead. However, by December 2007, only the German publicly owned railway company Deutsche Bahn and the Dutch transport company NedRail reportedly remained in the bidding contest. In January 2008, Laing Rail was purchased by Deutsche Bahn; accordingly Chiltern Railways became a part of the DB Regio group. During early 2011, the company was restructured, with DB Regio becoming a subsidiary of Arriva UK Trains.

During May 2011, Chiltern took over operating services on the Oxford–Bicester line from First Great Western. On 26 October 2015, the company opened two new stations, and , providing services between north Oxford and London Marylebone. In December 2016, Chiltern Railways started running train services from Oxford to London Marylebone.

In 2021, following the COVID-19 emergency measures, Chiltern was awarded a new direct contract by the DfT, replacing its franchise agreement, with a core term until 1 April 2025 and expiring on 12 December 2027. The end of the franchise was subsequently brought forward to 2026, with a date currently to be confirmed.

Chiltern Railways is one of several train operators impacted by the 2022–2024 United Kingdom railway strikes, the first national rail strike in the UK for three decades. Its workers were amongst those are participating in industrial action due to a dispute over pay and working conditions.

On 21 October 2024 Chiltern Railways, along with Great Western Railway began testing trains on the full route of stage 1 of East West Rail between and , ahead of its 2025 opening. In March 2025, the DfT confirmed that Chiltern Railways would be the operator of passenger services between Oxford and Milton Keynes, to start later in 2025.

The Chiltern Railways contract came to an end on 20 September 2026, at this point, its passenger services were renationalised and transferred from the private operator, Arriva UK Trains, into state ownership under DfT Operator. This transition is part of the UK government's broader rail reform programme initiated by the Passenger Railway Services (Public Ownership) Act 2024.

Services

Chiltern Railways operated regular services on five routes.

The Chiltern Main Line was the core route for the majority of Chiltern Railways services and was one of two "mainline routes" operated by the company. The route linked the major cities of London and Birmingham (Marylebone and Moor Street stations respectively), passing through the towns of High Wycombe, Banbury, Royal Leamington Spa, Warwick and Solihull. Chiltern Railways operated trains along the entire line, services ranging from stopping suburban trains (e.g. London Marylebone – Gerrards Cross) to express trains running the full length of the line between London and Birmingham. The fastest timetabled journey from Birmingham to London by this route was 99minutes (compared with 82minutes using Avanti West Coast services between and via the West Coast Main Line). In addition to the Chiltern Railways services, CrossCountry also operates regular services on the line north of Banbury, and West Midlands Trains operates regular services north of .

The London–Aylesbury line is the second "mainline route" operated by the company. The route links London Marylebone with Aylesbury via Amersham. All Chiltern Railways services on this route run the full length of the line between Marylebone and Aylesbury stations and call at all stations north of Rickmansworth; most trains are extended one station further to Aylesbury Vale Parkway. Certain peak hour services skip some or all stations between Marylebone and Great Missenden. The line runs alongside London Underground's Metropolitan line between (just north of Marylebone station) and just , each operator running on separate tracks. Beyond Harrow-on-the-Hill, the tracks are shared between Chiltern Railways and Metropolitan line services. This is an example of National Rail services using non-Network Rail tracks, and it uses a unique unregulated track-access agreement with London Underground. Beyond Amersham (where the Metropolitan line terminates), all services are operated by Chiltern Railways only.